An autogenous transplant of the kidney will function normally or maintain the life of the animal for several months or years. On the other hand, a homogenous transplant of the kidney will excrete urine for only a limited period and then rather abruptly cease to function. This peculiarity in the behavior of the homogenous transplant has been variously explained, but without the support of any definite evidence explanations can at best be purely hypothetic. Although it seems obvious that some light might be shed on the subject by knowledge of the histologic changes which take place in a homogenous transplanted kidney both before and after it has failed to excrete urine, such data are yet to be obtained.
The purpose of this investigation is to study the histologic changes that take place in the transplanted kidneys from day to day and to note any qualitative or quantitative difference in the